In products such as the wristwatch marketed under the registered trademark T-Touch®, the electrical connection between the tactile keys structured on the bottom surface of the crystal and the printed circuit board is achieved by means of elastomer connectors, also known under the trade name of Zebra® connectors.
These elastomer connectors are formed of a series of alternate conductive and insulating layers typically made of elastomer. These elastomer connectors, which provide high-density connections for electrical paths, are typically disposed between the middle part of the watch and a flange which covers the edge of the dial and which conceals the elastomer connectors from the view of the watch user when the user examines his watch from the side.
Two components, namely an elastomer connector and a flange, are therefore necessary to ensure the electrical connection between the tactile keys and the printed circuit board.
Further, in order to totally conceal the elastomer connectors from the view of the watch user, it is also necessary to cover the peripheral edge of the crystal by means of a bezel or to print an opaque ink layer underneath the surface of the crystal. The bezel has the drawback of reducing the apparent aperture of the crystal and of increasing the thickness of the watch. This solution also has the drawback of not being very attractive, in particular in the case of ladies' watches. Likewise, printing an ink layer underneath the surface of the crystal also has the drawback of reducing the apparent aperture of the crystal. Further, it is difficult to match the print colour to that of the dial. Finally, if the crystal is viewed from the side, a discontinuity can be seen where the print is located.